Authors : A.M.A. Rashad, D.K. EL- Hedainy and A.E. Mahdy
Abstract: Data from 3739 records of 1431 Holstein-Friesian cows belong to large commercial dairy farm in Egypt were studied to retrospectively determine the association between length of dry period and subsequent lactation milk yield, reproduction, lifetime yield and udder health status and to find out the adequate dry period length that maximizes milk production, lifetime milk yield and improves reproductive efficiency. Dry period lengths between ≤35 and ≥120 days were classified into eight categories with equal intervals. Sire, parity, year and season of calving affected Dry Period Length (DPL). Total 305 days milk yields increased with increasing DPL up to 78-91 days but decreased thereafter. Days open and calving interval of the subsequent lactation tended to decrease for short dry periods. Dry period of 64-77 days had the longest length of productive life (p<0.001) and the largest number of complete lactations, total lifetime milk yield and lifetime daily milk yield. Negative relations between DPL with total, 305 days and lifetime milk yields (p<0.050) but positive (p<0.010) with days open were found. The dry period category of 64-77 days was adequate for the best subsequent lactation performance in Holstein cows under study.
A.M.A. Rashad, D.K. EL- Hedainy and A.E. Mahdy, 2019. Effect of Dry Period Length on the Subsequent Lactation Performance in Holstein Cows under Subtropical Conditions. Journal of Animal and Veterinary Advances, 18: 24-29.